Secure internal telephone networks are commonly used by large corporations, educational institutions and government agencies. Typically, a network user can connect to another user by simply dialing an extension number (e.g., a 4-digit extension). The network typically provides enhanced functionality such as call transfers, local network operator calls, voicemail checking, voicemail forwarding, and built-in conference calling capability.
One disadvantage of secure telephone networks is that many of the useful network functions (e.g. call transfers) can only be accessed from an extension within the network. This typically means that the user must be located within the office or building containing the network in order to use the network functions. There is no way to allow external users to access the network functions.
For example, a remote caller located at home, or calling from a cellular phone may dial an extension number internal to the network, but will be unable to transfer calls, transfer voicemail, or participate in conference calls internal to the phone network.
An additional disadvantage of this lack of access is that connections external to the network (e.g., requiring uses of a telephone company network) are relatively expensive compared to connections internal to the network.
With an increasing number of people working at home and away from the office, the ability to remotely access a secure, internal telephone network is greatly needed.
It would be an advance in the art of telephone networks to allow a remote user to access a secure telephone network, and make use of all the functionality the network offers. Remote access to the network should be guarded with a high level of security. It would be particularly useful for the connection method to be simple and transparent to the external user.
U.S. Pat. Nos. 6,571,094 and 6,141,545 each teach methods for remote call forwarding to users (e.g. cellular telephone users) outside a secure network. They do not teach how to dial into a secure telephone network.